HK explores underground caverns to fix land shortage problem

Hong Kong government is looking “down” for options to ease the tension of space shortage in the city. Some 48 caverns are being developed to accommodate non-residential facilities.

(Photo credit: Geotechnical Engineering Office of the Civil Engineering and Development Department)

Land and housing supply has always been an issue in the densely populated Hong Kong.

“Hong Kong is a high-density compact city and its topographical setting with steep natural hillsides significantly limits the extent for urban expansion,” said Manson Pang, geotechnical engineer at the government’s Civil Engineering and Development Department (CEDD). “The shortage of developable land forms a key driver to explore other sustainable and innovative approaches to expand land resources.”

Rock caverns are viable sources of land supply, which can provide solution space for a broad variety of land uses and help address problems encountered in the congested urban environment.

Since 2010, the Government has launched a number of strategic studies and pilot projects to explore the potential of systematic utilisation of rock caverns.

In the 2009-10 Policy Agenda, Hong Kong’s Development Bureau put forward an initiative to promote the enhanced use of rock caverns as part of Hong Kong’s pursuit of sustainable development.

A “Pilot Study on Underground Space Development in Selected Strategic Urban Areas” was launched in June 2015, covering four selected urban areas (Tsim Sha Tsui West, Causeway Bay and Happy Valley, and Admiralty/Wan Chai) with the aim to identify the potential for underground space developments, and to formulate a set of Underground Master Plans to guide the future underground space development.

In 2017, the government completed a new comprehensive feasibly study that identifies 48 caverns for long-term development, ranging in size from 0.1 to 0.8 square miles. Six more studies to push the project along are reportedly underway as well.

“With the society getting wealthier, people also have the aspiration to improve their quality of life…the use of underground space is one of the viable solutions to address such needs,” said Rupert Leung, managing director of Design and Engineering at asset design and consulting firm Arcadis.

However, the government is currently only considering moving non-residential real estate into these caverns since they are not that comfortable to live in.

“Cavern development will take time for implementation and it cannot offer a quick fix to the imminent problem of shortage of developable land, particularly when the subsurface land created by caverns is not suitable for residential uses,” said Pang from the CEDD.

“With progressive urban development, there are existing facilities, such as sewage treatment works and service reservoirs, which in past were rather remote, now being just at the verge of developed areas and already served by public roads and infrastructures,” Leung told Harbour Times. “Relocating these facilities into caverns to release the land for development is a sensible option.”

One recent successful example is the relocation of the service reservoirs near the University of Hong Kong into caverns to allow the land being developed into its Centennial Campus.

With all the benefits of caverns development aside, it is generally more costly and lengthy than other land supply options- the rock cavern excavation alone can range from $190 to $250 per cubic foot. A cavern development project may also take a long lead time of eight to ten years or more from its conception to realisation.